[Code of Federal Regulations]
[Title 49, Volume 5]
[Revised as of October 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 49CFR393.41]

[Page 400-401]
 
                        TITLE 49--TRANSPORTATION
 
                      DEPARTMENT OF TRANSPORTATION
 
PART 393_PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION--Table of 
Contents
 
                            Subpart C_Brakes
 
Sec.  393.41  Parking brake system.

    (a) Hydraulic-braked vehicles manufactured on or after September 2, 
1983. Each truck and bus (other than a school bus) with a GVWR of 4,536 
kg (10,000 pounds) or less which is subject to this part and school 
buses with a GVWR greater than 4,536 kg (10,000 pounds) shall be 
equipped with a parking brake system as required by FMVSS No. 571.105 
(S5.2) in effect at the time of manufacture. The parking brake shall be 
capable of holding the vehicle or combination of vehicles stationary 
under any condition of loading in which it is found on a public road 
(free of ice and snow). Hydraulic-braked vehicles which were not

[[Page 401]]

subject to the parking brake requirements of FMVSS No. 571.105 (S5.2) 
must be equipped with a parking brake system that meets the requirements 
of paragraph (c) of this section.
    (b) Air-braked power units manufactured on or after March 1, 1975, 
and air-braked trailers manufactured on or after January 1, 1975. Each 
air-braked bus, truck and truck tractor manufactured on and after March 
1, 1975, and each air-braked trailer except an agricultural commodity 
trailer, converter dolly, heavy hauler trailer or pulpwood trailer, 
shall be equipped with a parking brake system as required by FMVSS No. 
121 (S5.6) in effect at the time of manufacture. The parking brake shall 
be capable of holding the vehicle or combination of vehicles stationary 
under any condition of loading in which it is found on a public road 
(free of ice and snow). An agricultural commodity trailer, heavy hauler 
or pulpwood trailer shall carry sufficient chocking blocks to prevent 
movement when parked.
    (c) Vehicles not subject to FMVSS Nos. 105 and 121 on the date of 
manufacture. (1) Each singly driven motor vehicle not subject to parking 
brake requirements of FMVSS Nos. 105 or 121 at the time of manufacturer, 
and every combination of motor vehicles must be equipped with a parking 
brake system adequate to hold the vehicle or combination on any grade on 
which it is operated, under any condition of loading in which it is 
found on a public road (free of ice and snow).
    (2) The parking brake system shall, at all times, be capable of 
being applied by either the driver's muscular effort or by spring 
action. If other energy is used to apply the parking brake, there must 
be an accumulation of that energy isolated from any common source and 
used exclusively for the operation of the parking brake.


Exception: This paragraph shall not be applicable to air-applied, 
mechanically-held parking brake systems which meet the parking brake 
requirements of FMVSS No. 121 (S5.6).
    (3) The parking brake system shall be held in the applied position 
by energy other than fluid pressure, air pressure, or electric energy. 
The parking brake system shall not be capable of being released unless 
adequate energy is available to immediately reapply the parking brake 
with the required effectiveness.

[70 FR 48048, Aug. 15, 2005]